- What it is. This potassium nitrate is ACS reagent-grade white crystals, offered in 1 lb, 2.5 kg, and 10 kg sizes. It is a high-purity salt for electrolytes, standards, salt bridges, crystallization work, and laboratory and industrial applications.
- What ACS grade guarantees. ACS reagent potassium nitrate assays at 99.0% minimum, with limits on chloride (0.002%), nitrite (0.001%), sulfate (0.003%), iodate and phosphate (5 ppm each), heavy metals (5 ppm), and iron (3 ppm). A 5% solution has a pH of 4.5-8.5.
- Chemical identity. Potassium nitrate (saltpeter, CAS 7757-79-1, KNO3, 101.10 g/mol) is a white crystalline salt that melts at about 334 °C. It is highly soluble in hot water and much less soluble in cold water, which makes it a classic example for recrystallization.
- An oxidizer. At high temperatures, potassium nitrate releases oxygen and strongly supports combustion, which is why it is used in pyrotechnics and black powder. As an oxidizer, store it away from combustible materials.
- Laboratory uses. Labs use ACS potassium nitrate to prepare ionic strength adjusters and electrolytes, salt bridges and reference electrode filling solutions, nitrate standards for ion chromatography and ion-selective electrodes, and in solubility and crystallization teaching experiments.
- Agriculture and industry. Potassium nitrate supplies potassium and nitrogen as a soluble fertilizer; it is used in heat transfer and molten salt baths, glass and ceramic manufacturing, and as a curing agent in some food applications.
- Sizes. The 1 lb size (ZP1526-450) suits analytical labs and teaching, the 2.5 kg size (PN9556-25) suits labs with steady, moderate use, such as teaching labs and electrochemistry groups, and the 10 kg size (ZP1526-KG) supports pilot work, larger electrolyte batches, and production.
- Recrystallization teaching. Because potassium nitrate's solubility rises steeply with temperature, a hot saturated solution deposits large crystals as it cools. That behavior makes it a standard compound for teaching solubility curves and purification by recrystallization.
- Handling at a glance. Potassium nitrate is an oxidizer that may intensify fire. Keep it away from heat, flames, and combustible materials; avoid creating dust, and wear safety glasses and gloves when handling.
Technical Specifications
| Chemical Name | Potassium nitrate |
| CAS Number | 7757-79-1 |
| EC Number | 231-818-8 |
| Synonyms | Nitrate of potash, saltpeter, niter |
| Formula | KNO3 |
| Molecular Weight | 101.10 g/mol |
| Grade | ACS reagent |
| Assay | 99.0% min |
| pH (5% solution, 25 °C) | 4.5 to 8.5 |
| Insoluble Matter | 0.005% max |
| Chloride (Cl) | 0.002% max |
| Nitrite (NO2) | 0.001% max |
| Sulfate (SO4) | 0.003% max |
| Iodate (IO3) | 5 ppm max |
| Phosphate (PO4) | 5 ppm max |
| Calcium (Ca) | 0.005% max |
| Magnesium (Mg) | 0.002% max |
| Sodium (Na) | 0.005% max |
| Heavy Metals (as Pb) | 5 ppm max |
| Iron (Fe) | 3 ppm max |
| Melting Point | About 334 °C |
| Density | About 2.109 g/cm³ |
| Form | White crystals |
| Hazard Statement | H272 (may intensify fire; oxidizer) |
| DOT | UN1486, Potassium nitrate, Class 5.1, PG III |
| Package Sizes | 1 lb; 2.5 kg; 10 kg |
Available Variants
- ZP1526-450: 1 lb for analytical labs and teaching.
- PN9556-25: 2.5 kg for labs with steady, moderate use.
- ZP1526-KG (PN9556-10): 10 kg for pilot work and production.
Applications / Common Uses
- Salt bridges: Prepares inert electrolyte for electrochemical cells.
- Electrode filling solutions: Supports double-junction reference electrodes.
- Nitrate standards: Prepares calibration standards for nitrate analysis.
- Crystallization teaching: Demonstrates temperature-dependent solubility.
- Fertilizer and industry: Supplies potassium and nitrate for process use.
Storage, Handling & Shipping
Store in a cool, dry place in a tightly closed container, away from combustible materials, organic matter, reducing agents, powdered metals, and acids. As an oxidizer, do not store potassium nitrate with flammables or fuels. Keep it dry, since it can cake in humid conditions.
- Incompatible materials: Combustible and organic materials, reducing agents, powdered metals, sulfur, and strong acids.
- Personal protection: Safety glasses, gloves, and dust control.
- Spill response: Sweep up without raising dust, keep away from combustibles, and place in a closed container for disposal.
- First aid: Eyes: rinse with water for several minutes. Ingestion: seek medical advice.
- GHS signal word: Warning (oxidizer).
- DOT / shipping: UN1486, Potassium nitrate, Class 5.1, PG III.
Related Categories & Services
- Shop ACS Grade Laboratory Chemicals for related products in this category.
- Explore Inorganic Chemicals and Oxidizers.
- Vendor Managed Inventory (VMI) Program: Lab Pro can stock, track, and replenish this item on site so it never runs out. Contact info@labproinc.com or 888-452-2776 to set up a VMI assessment.
